As a psychiatrist, my patients often ask me if there are dietary changes they can make to improve their depression. Many cannot tolerate antidepressants, don’t benefit from them, or are reluctant to try medications or seek counseling due to stigma. As a result, they miss an average of 19 work days per year, costing employers up to $44 billion dollars a year in lost productivity. Depression can aggravate other chronic illnesses as well, like diabetes and heart disease. We know that plant-based diets prevent and even treat these chronic illnesses, but can they also improve mood? Our recent study published in the March/April issue of the American Journal of Health Promotion demonstrates how a plant-based nutrition program improves not only depression, but anxiety, fatigue, productivity, and other markers of well-being.

This 18-week study analyzes the health benefits of adopting a plant-based vegan diet in a corporate setting. Study participants, GEICO employees who were either overweight or struggling with type 2 diabetes, adopted a low-fat vegan diet, favoring high-fiber, low-glycemic foods. They learned about preventive nutrition and new cooking tips through weekly “lunch and learn” sessions led by a clinician or cooking instructor. They also formed bonds, sharing helpful health tips along the way and connecting with the group on a daily basis through an online forum. Study participants alleviated symptoms of anxiety, depression, and fatigue, and improved their productivity both at work and outside of work, according to the 36-Item Short Form Health Survey (SF-36) and the Work Productivity and Activity Impairment Questionnaire (WPAI):

They also lost an average of 10 pounds, lowered LDL cholesterol levels by 13 points, and improved blood sugar control, if they had type 2 diabetes. When people improve their physical health they become more physically and socially active and their overall quality of life improves.

How does a plant-based diet improve depression? Depression is related to inflammation in the body and low levels of serotonin. Plant-based foods naturally lower inflammation in the body because they are naturally low in fat and high in antioxidants. High vegetable intake increases the amount of B vitamins in the diet, which have been found to affect mood.

So what are you waiting for? Jump right in with a low-fat, plant-based diet! It’s the best prescription to boost your mood, energy, and productivity, while reducing your risk for chronic illnesses. I know I’ll be prescribing a plant-based diet to all of my patients for their emotional and physical well-being.

Ulka Agarwal, M.D., is the lead physician and psychiatrist at California State University, East Bay, where she developed and leads a plant-based employee wellness nutrition program. Dr. Agarwal is the former chief medical officer for the Physicians Committee and a graduate of Dr. Andrew Weil’s Integrative Medicine Fellowship through the University of Arizona.

Today, the Dietary Guidelines Advisory Committee released its report on what Americans should eat. When finalized, the Guidelines will be the basis for all federal programs, including school lunches. And the report is a huge step forward in several ways:

The report singled out vegetarian diets as one of three healthful diet patterns. The other two healthy patterns were the Mediterranean diet and the “Healthy U.S.-style Pattern.” Vegetarian diets reduce the risk of obesity, diabetes, and other health problems and have gained greater prominence in each new edition of the Guidelines.

The report was a rebuke for those who have suggested that saturated (“bad”) fat, common in meat and dairy products, is somehow not a danger. The report emphasized saturated fat’s risks and maintained the previous limit that no more than 10% of calories should come from saturated fat.

The report deleted “lean meat” from its list of favored foods. Its authors were convinced by evidence showing that increased consumption of “lean meat” confers no health benefits.

The report breaks new ground in reporting on food’s relationship to environmental health, which in turn affects human health.

But for all its good points, the new report has trouble spots:

The report suggested that cholesterol in foods is not a major danger, contrasting with the Institute of Medicine, which found that cholesterol in foods does indeed raise blood cholesterol levels, especially in people whose diets are modest in cholesterol to start with. On this topic, the Dietary Guidelines Advisory Committee did no original research and instead deferred to a 2014 report by the American Heart Association and American College of Cardiology. However, the American Heart Association receives substantial cash payments for certifying food products, including cholesterol-containing food products as “heart healthy,” creating a financial incentive for discounting the relationship between dietary cholesterol and serum cholesterol.

The Physicians Committee is concerned that exonerating dietary cholesterol will only confuse an already bewildered public. Most people do not differentiate fat from cholesterol, or dietary cholesterol from blood cholesterol. To suggest that cholesterol in foods is not a problem will lead many to imagine that fatty foods or an elevated blood cholesterol level carry no risk—two potentially disastrous notions.

Accordingly, the Physicians Committee has petitioned the USDA and DHHS to disregard the Dietary Guidelines Advisory Committee’s findings on dietary cholesterol. The reliance on the American Heart Association document does not comply with the spirit of the Federal Advisory Committee Act, which sets standards for bias among federal advisory committees.

The Committee report recommends fish, despite frequent contamination with mercury and PCBs, and despite evidence that vegetarians who avoid fish and shellfish are slimmer and have less risk of diabetes, compared with people who eat fish.

The report continued to recommend dairy products, despite recent evidence that they do not “build strong bones” or protect against fractures.

Even with its flaws, the new Dietary Guidelines report is a major advance.

The Physician Committee’s own recommendations, represented graphically in The Power Plate (www.ThePowerPlate.org), focus on whole grains, vegetables, fruits, and legumes as dietary staples. The Power Plate rests on hundreds of scientific studies showing that plant-based eating habits are associated with lower obesity rates and a reduced risk of heart disease, hypertension, and type 2 diabetes.

Fiber plays a key role for digestion, weight loss, and cancer prevention, and can even increase lifespan! But don’t be fooled—many packaged food companies are trying to boost sales by adding extra fiber to their gummy candy or yogurt, but the best source of fiber is plants themselves! Yes, natural fiber is found only in fruits, vegetables, whole grains, and legumes. So make sure you’re filling your plate with whole, plant-based foods.

What is fiber?

There are two types of fiber: soluble and insoluble. Soluble fiber is found in oats, beans and other legumes, and some fruits and vegetables. Soluble fiber lowers cholesterol levels. Insoluble fiber—found in whole grains, fruits and vegetables, kidney beans, and bran—acts like a broom, cleaning your digestive tract.

Both types of fiber are only found in plant foods—meat and dairy products contain no natural fiber. Don’t be fooled by yogurts that prominently advertise their fiber content! That fiber was added during processing. Since dairy products are high in saturated fat and cholesterol, skip the yogurt and head to the produce aisle. Just one cup of raspberries has 8 grams of fiber! One cup of red lentils has 16 grams of fiber—and 18 grams of protein.

Weight Loss

If you’re looking to lose weight, filling up on fiber-rich foods is your best bet. My colleagues and I recently published a study in the Journal of the Academy of Nutrition and Dietetics showing that simply switching to a plant-based diet leads to significant weight loss, without any calorie counting or exercise.

Cancer Prevention

Not only can fiber help you shed pounds or relieve your digestive woes, it can decrease cancer risk. By improving the intestinal transit of food and waste, fiber helps your body eliminate carcinogens. The U.S. Polyp Prevention Trial also found that a high-fiber diet reduced the occurrence of colon polyps. A meta-analysis published in the Journal of the National Cancer Institute examined 13 studies and found that the risk of colorectal cancer decreased as fiber intake increased.

How Can I Get Enough Fiber Each Day?

I recommend a dietary intake of 40 grams of fiber per day—while most Americans are only getting 10-15 grams. But there’s no need to count. It’s easy to boost your fiber content with a few easy swaps. Trade white bread for whole grains. Ditch sugary cereals for heart-healthy oatmeal. Add some fruit to your breakfast or grab an apple or banana when you’re in a hurry. Make sure that everything on your plate has at least a little bit of fiber. Most importantly, skip the animal products. When your menu is plant-strong, you’ll be getting the fiber you need.